The perovskite-based oxide Y 0.33 Sr 0.67 CoO 2.79 has been magnetically and structurally characterized. The material shows a unit cell of 2ϫ2ϫ4 simple perovskite cubes with space group I4/mmm. This is a different structure to that observed in the much-studied (La,Sr)CoO 3 oxides. Oxygen stoichiometry is established through thermogravimetric analysis and correlated with ac and dc magnetic measurements and magnetic neutron diffraction. Hysteresis with field and temperature is observed in the dc magnetization measurements, yet the absence of an imaginary component in the ac susceptibility suggests a time-independent cause for these effects such as the presence of independently ordering ferromagnetic regions due to compositional inhomogeneities within the ͑single-phase͒ sample. Rietveld magnetic refinements suggest that the Co moments are arranged antiferromagnetically below 320 K, with the ferromagnetic regions existing within the long-range ordered antiferromagnetic matrix. The staggered moments are ͑anti͒parallel with the c axis and of magnitude 2 B , a moment most typical of intermediate spin Co 3ϩ . The material does not enter a spin glass or cluster glass phase, but appears to undergo a broad spin-state transition below 100 K.

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[This paper is part of the Focused Collection on Gender in Physics.] We have investigated gender differences in performance over the past eight years on the Australian Science Olympiad Exam (ASOE) for physics, which is taken by nearly 1000 high school students each year. The ASOE, run by Australian Science Innovations (ASI), is the initial stage of the process of selection of teams to represent Australia at the Asian and International Physics Olympiads. Students taking the exam are generally in their penultimate year of school and selected by teachers as being high performing in physics. Together with the overall differences in facility, we have investigated how the content and presentation of multiple-choice questions (MCQs) affects the particular answers selected by male and female students. Differences in the patterns of responses by male and female students indicate that males and females might be modeling situations in different ways. Some strong patterns were found in the gender gaps when the questions were categorized in five broad dimensions: content, process required, difficulty, presentation, and context. Almost all questions saw male students performing better, although gender differences were relatively small for questions with a more abstract context. Male students performed significantly better on most questions with a concrete context, although notable exceptions were found, including two such questions where female students performed better. Other categories that showed consistently large gaps favoring male students include questions with projectile motion and other two-dimensional motion or forces content, and processes involving interpreting diagrams. Our results have important implications, suggesting that we should be able to reduce the gender gaps in performance on MCQ tests by changing the way information is presented and setting questions in contexts that are less likely to favor males over females. This is important as MCQ tests are frequently used as diagnostic tests and aptitude tests as well as to assess learning. DOI: 10.1103/PhysRevPhysEducRes.12.020111 I. MOTIVATIONEach September, nearly 1000 Australian high school students take the Australian Science Olympiad Exam (ASOE) for physics. On the basis of performance in the ASOE, approximately 24 students are chosen to attend a summer school "training camp" in January of the following year. The top eight students from the summer school make up the Australian team for the Asian Physics Olympiad (APhO) in April of that year, and five of these students go on to attend the International Physics Olympiad (IPhO) in July. The ASOE is the thus the first hurdle in an intensive selection and training process.The students who take the ASOE are selected by their teachers as being of high ability in physics, and are mainly in year 11 (the penultimate year of high school) and about 16 years old. Typically between a quarter and a third of these students are female, which is approximately the same fraction as the total year 11 physics cohort. How...

Undergraduate research experiences are being incorporated into degree programs with increasing frequency. However, there has been little study into their effectiveness in preparing students for research or into the learning gains that students realise from one or more research experiences. We surveyed science students in an elite, research-based undergraduate degree program at a researchintensive university. These students complete six research projects during their degree and we aimed to delineate factors that students perceive as leading to either good or bad experiences. Two factors stand out as contributing to a successful research experience: the supervisor, with students reporting both pedagogic and affective benefits of good supervision; and the feeling that they are doing authentic science. Surprisingly, given the research-intensive nature of this degree, the learning gains students report relate to both an appreciation of what research is like and life skills, such as time management, rather than scientific thinking skills.

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